Light source device having first light source, second light source, and control section to control drive timing of first light source and second light source such that drive pattern of second light source is inversion of drive pattern of first light source, and projection apparatus and projection method which utilize said light source device

ABSTRACT

A light source device includes a first light source configured to emit light within a first wavelength band, a second light source configured to emit light within a second wavelength band, and a light source control section configured to control drive timing of the first light source with a first drive pattern, and to control drive timing of the second light source with a second drive pattern which is an inverted pattern of the first drive pattern of the first light source, such that a light emission period for light-source light using light emitted by the second light source is positioned between light emission periods for the light-source light emitted by the first light source, and such that a frequency of the light-source light using light emitted by the second light source is higher than a frequency of light emitted by the first light source.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Divisional of U.S. application Ser. No. 12/825,615, filed Jun.29, 2010, which is based upon and claims the benefit of priority fromprior Japanese Patent Application No. 2009-156092, filed Jun. 30, 2009,the entire contents of both of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a light source device, a projectionapparatus, and a projection method that are suitable for a Digital LightProcessing (DLP [registered trademark]) data projector apparatus and thelike.

2. Description of the Related Art

Displaying colors with a projection display apparatus requires planarlight sources that emit the primary colors of red, green, and blue, andspatial optical modulators corresponding to the primary colors.Therefore, the increase in the number of parts hinders reduction in thesize, weight, or cost of the entire device. For example, Jpn. Pat.Appin. KOKAI Publication No. 2004-341105 discloses the technology inwhich a light-emitting diode that emits ultraviolet light is used as alight source and the ultraviolet light is emitted to a color wheel,thereby producing visible light corresponding to red, green, and blue.Specifically, a visible light reflection film that transmits ultravioletlight and reflects visible light is formed on the light source side ofthe color wheel, and a phosphor layer that emits visible lightcorresponding to red, green, and blue by being illuminated withultraviolet light is formed on the back of the color wheel.

However, when the invention described in Jpn. Pat. Appin. KOKAIPublication No. 2004-341105 mentioned above is adopted, the presentlyknown various red phosphors are significantly lower in light emissionefficiency, compared to green and blue phosphors, resulting ininadequate red luminance.

When a brighter projected image is formed by giving priority toluminance, white balance is lost, with the result that colorreproducibility degrades. Conversely, giving priority to white balanceand hence color reproducibility decreases the overall luminance of aprojected image because of the low luminance of the red image, resultingin a dark image.

The present invention has been made in view of the foregoing problems ofconventional technologies. It is accordingly an object of the presentinvention to provide a light source device, a projection apparatus, anda projection method, which convert light from a light source into aplurality of colors by using, e.g., a color wheel, use another lightsource, and stabilize drive while taking into account the light emissioncharacteristics of each of the light sources, thereby making colorreproducibility compatible with the brightness of a projected image.

BRIEF SUMMARY OF THE INVENTION

According to one aspect of the present invention, there is provided alight source device comprising: a first light source configured to emitlight within a first wavelength band; a light-source light productionsection configured to sequentially produce light-source light of aplurality of colors at predetermined frequency by using light emitted bythe first light source; a second light source configured to emit lightwithin a second wavelength band different from the first wavelengthband; and a light source control section configured to control drivetiming for each of the first and second light sources such that a lightemission period for light-source light using light emitted by the secondlight source is positioned between light emission periods for thelight-source light of the plurality of colors produced by thelight-source light production section and that the light-source lightusing light emitted by the second light source has a frequency higherthan that of the light-source light production section.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the invention, andtogether with the general description given above and the detaileddescription of the embodiments given below, serve to explain theprinciples of the invention.

FIG. 1 is a block diagram illustrating the overall configuration of thefunction of a circuit provided for a data projector apparatus accordingto one embodiment of the present embodiment;

FIG. 2 mainly illustrates the detailed optical configuration of a lightsource system according to the embodiment;

FIG. 3 is a plan view of the configuration of a fluorescent color wheelaccording to the embodiment;

FIG. 4 is a timing chart illustrating the content of a driving processfor an optical system in one image frame according to the embodiment;

FIG. 5 is a plan view of another configuration of the fluorescent colorwheel according to the embodiment; and

FIG. 6 is a timing chart illustrating the content of another drivingprocess for the optical system in one image frame according to theembodiment.

DETAILED DESCRIPTION OF THE INVENTION

Preferred embodiments of the present invention will now be describedwith reference to the drawings. In the embodiments described below,various technically preferred limits are set for carrying out theinvention, but the scope of the invention is not limited to thefollowing embodiments or examples shown in the drawings.

Using an example where the present invention is applied to a DigitalLight Processing (DLP [registered mark]) data projector apparatus, thepresent invention will be described with reference to the drawings.

FIG. 1 is a block diagram schematically illustrating the configurationof the function of an electronic circuit included in a data projectorapparatus 10 according to the present embodiment.

An input/output connector section 11 includes, for example, an RCA[Radio Corporation of America] pin jack video input terminal, D-sub 15RGB input terminal, and Universal Serial Bus (USB) connector.

Image signals of various specifications input from the input/outputconnector section 11 are input to an image conversion section 13(generally called a scaler) via an input/output interface 12 and asystem bus SB.

The image conversion section 13 converts the input image signals intouniform image signals of predetermined format suitable for projection,then stores these image signals in a video RAM 14 (i.e., a buffer memoryfor display) as needed, and transmits them to a projection imageprocessing section 15.

At this time, data such as symbols representing various operatingconditions for on-screen display (OSD) are superposed on the imagesignals by the video RAM 14 if necessary, and the image signals thusprocessed are transmitted to the projection image processing section 15.

According to the transmitted signals, the projection image processingsection 15 drives and displays a micromirror element 16 (i.e., spatiallight modulation [SLM] element) through a higher-speed time divisiondrive determined by multiplying the frame rate (which is based on apredetermined format), for example, 120 frames/sec, the number ofcomponents into which color is divided, and gradation for display.

The micromirror element 16 individually on/off operates the angles ofinclination of a plurality of minute mirrors at high speed. The minutemirrors provided for, for example, extended graphics array (XGA) (1024horizontal pixels×768 vertical pixels) are arranged in an array. Therebythe micromirror element 16 forms an optical image with light reflectedby the micromirrors.

Meanwhile, a light source section 17 emits red (R), green (G), and blue(B) primary color components in a circulatory and time-division manner.The primary color components from the light source section 17 aretotally reflected by a mirror 18 and the micromirror element 16 isthereby illuminated by the light components.

Then, an optical image is formed with the light components reflected bythe micromirror element 16. The optical image thus formed is projectedand displayed on a screen (not shown), which is a projection target, viaa lens unit 19.

The light source section 17, a detailed configuration of which will bedescribed below, comprises two light sources, namely, a semiconductorlaser 20 that emits blue laser light and an LED 21 that emits red light.

The blue laser light emitted by the semiconductor laser 20 is totallyreflected by a mirror 22, then transmitted through a dichroic mirror 23,and converges on one point of the circumference of a color wheel 24,thereby illuminating the color wheel. A motor 25 rotates the color wheel24. On the circumference of the color wheel 24 illuminated by the laserlight, a green phosphor reflective plate and a blue diffusing plate arecombined in the shape of a ring.

When the green phosphor reflective plate of the color wheel 24 is in aplace illuminated by laser light, green light is excited by illuminationwith laser light. The excited green light is reflected by the colorwheel 24, and is also reflected by the dichroic mirror 23. Thereafter,this green light is reflected by another dichroic mirror 28, and isformed into a luminous flux of substantially uniformly distributedluminance by an integrator 29. Then, the luminous flux is totallyreflected by a mirror 30 and transmitted to the mirror 18.

When the diffusing plate is located in a place illuminated by laserlight, the laser light is passed through the color wheel 24 while beingdiffused by the diffusing plate, and is then totally reflected bymirrors 26 and 27. Thereafter, this blue light is transmitted throughthe dichroic mirror 28 and formed into a luminous flux of substantiallyuniformly distributed luminance by the integrator 29. Then, the luminousflux is totally reflected by the mirror 30 and transmitted to the mirror18.

Red light emitted by the LED 21 is transmitted through the dichroicmirror 23 and then reflected by the dichroic mirror 28, and formed intoa luminous flux of substantially uniformly distributed luminance by theintegrator 29. Then, the luminous flux is totally reflected by themirror 30 and transmitted to the mirror 18.

As described above, the dichroic mirror 23 has the spectral property ofreflecting green light while transmitting blue light and red light.

In addition, the dichroic mirror 28 has the spectral property ofreflecting red light and green light while transmitting blue light.

A projection light processing section 31 wholly controls the lightemission timings of the semiconductor laser 20 and LED 21 in the lightsource device 17, and the rotation of the color wheel 24 by the motor25. According to the timing of image data provided by the projectionimage processing section 15, the projection light processing section 31controls the light emission timings of the semiconductor laser 20 andLED 21, and rotation of the color wheel 24.

A CPU 32 controls operation of all the circuits. The CPU 32 uses a mainmemory 33 comprising a DRAM, and a program memory 34 comprising anelectrically writable non-volatile memory that stores operating programsand various fixed data, etc., to control operations inside the dataprojector apparatus 10.

The CPU 32 performs various projection operations according to keyoperating signals output from an operating section 35.

The operating section 35 includes a key operating section provided onthe main body of the data projector apparatus 10 and a laser receivingsection that receives infrared light from a remote controller, notshown, specially provided for the data projector apparatus 10. A keyoperating signal based on a key operated by a user through the keyoperating section of the main body or through the remote controller isdirectly output to the CPU 32 by the operating section 35.

In addition to the key operating section and remote controller, theoperating section 35 comprises, for example, a focus adjustment key,zoom adjustment key, input switching key, menu key, cursor (←, →, ↑, ↓)keys, set key, cancellation key, etc.

Further, the CPU 32 is connected to an audio processing section 36 viathe system bus SB. The audio processing section 36 comprises a pulsecode modulation (PCM) audio source circuit. The audio processing section36 analogizes audio data provided for a projection operation, drives aloudspeaker 37 to intensify and emit audio, or produces a beep ifnecessary.

FIG. 2 mainly illustrates an example of the detailed configuration of anoptical system of the light source section 17. FIG. 2 shows a planarlayout of the configuration of the light source section 17.

In this case, for example, three semiconductor) lasers 20A to 20C withthe same light emission characteristics are provided. Each of thesemiconductor lasers 20A to 20C emits blue laser light having awavelength of, for example, 450 nm.

The blue light emitted by the semiconductor lasers 20A to 20C is totallyreflected by corresponding mirrors 22A to 22C via lenses 41A to 41C,transmitted through the dichroic mirror 23 via lenses 42 and 43, andthen illuminates the color wheel 24 via a lens group 44.

FIG. 3 illustrates the configuration of the color wheel 24 according tothe present embodiment. As shown in FIG. 3, on the color wheel 24, onering is formed from a combination of a green phosphor reflective plate24G and a blue diffusing plate 24B, each of which is a semicircular ringwith a central angle of 180°.

When the green phosphor reflective plate 24G of the color wheel 24 is ina place illuminated by blue light, green light with a wavelength band,the central wavelength of which is, for example, about 530 nm is excitedby the illumination. The excited green light is reflected by the colorwheel 24 and then also reflected by the dichroic mirror 23 via the lensgroup 44.

The green light reflected by the dichroic mirror 23 is further reflectedby the dichroic mirror 28 via a lens 45. Then, this light is formed intoa luminous flux of substantially uniformly distributed luminance by theintegrator 29 via a lens 46. The luminous flux is then totally reflectedby the mirror 30 via a lens 47 and sent to the above-mentioned mirror 18via a lens 48.

The green light totally reflected by the mirror 18 illuminates themicromirror element 16 via a lens 49. Subsequently, an optical image fora green component is formed with the reflected green light, and isprojected outward via the lens 49 and projection lens unit 19.

In addition, when the blue diffusing plate 24B of the color wheel 24 isin a place illuminated by blue light, the blue light is transmittedthrough the color wheel 24 while being diffused by the diffusing plate24B. Then, the blue light is totally reflected by the mirror 26 via alens 50 disposed behind the color wheel 24.

Further, the blue light is totally reflected by the mirror 27 via a lens51, and transmitted through the dichroic mirror 28 via a lens 52.Thereafter, this light is formed into a luminous flux of substantiallyuniformly distributed luminance by the integrator 29 via the lens 46.The luminous flux is then totally reflected by the mirror 30 via thelens 47 and sent to the above-mentioned mirror 18 via the lens 48.

The LED 21 produces red light having a wavelength of, for example, 620nm. The red light emitted by the LED 21 is transmitted through thedichroic mirror 23 via a lens group 53, and reflected by the dichroicmirror 28 via the lens 45. Further, this light is formed into a luminousflux of substantially uniformly distributed luminance by the integrator29 via the lens 46. The luminous flux is then totally reflected by themirror 30 via the lens 47 and sent to the above-mentioned mirror 18 viathe lens 48.

Next, operation of the embodiment will be described.

In this case, the time ratio among the R, G, and B primary color imagescomposing one frame of a color image to be projected is 1:1:1. That is,if a time ratio r:g:b at which each of the R, G, and B primary colorimages is projected is replaced by the central angle of the color wheel24 relative to one rotation of the color wheel 24 through 360°,120°:120°:120° is yielded.

The drive timing of the color wheel by a conventional, general drivemethod is shown in FIG. 4(A) for reference. A conventional, generalcolor wheel is driven such that a cycle of R, G, and B segmentscorresponds to one frame.

By comparison, the color wheel 24 in the present embodiment isconfigured such that the green phosphor reflective plate 24G and theblue diffusing plate 24B bisect the circumference, as shown in FIG. 3.Therefore, the projection light processing section 31 ensures that onerotation corresponding to the two segments is synchronized with oneframe, as shown in FIG. 4(B).

The projection light processing section 31 trisects the period of thefront half frame in which the green phosphor reflective plate 24G of thecolor wheel 24 is present in the optical path of blue laser lightemitted from each of the semiconductor lasers 20A to 20C, and activatesand drives the LED 21 in the first ⅓ of each equal period, therebyproducing red light.

At this time, in synchronization with the activation of the LED 21, thesemiconductor lasers 20A to 20C stop the emission of blue laser light.

Similarly, the projection light processing section 31 trisects theperiod of the last half frame in which the blue diffusing plate 24B ofthe color wheel 24 is present in the optical path of blue laser lightemitted from each of the semiconductor lasers 20A to 20C, and activatesand drives the LED 21 in the first ⅓ of each equal period, therebyproducing red light.

At this time, in synchronization with the activation of the LED 21, thesemiconductor lasers 20A to 20C stop the emission of blue laser light.

FIG. 4(D) illustrates the timing of emitting blue laser light from thesemiconductor lasers 20A to 20C, and FIG. 4(E) illustrates the timing ofproducing red light with the LED 21.

Accordingly, the pattern of switching R, G, and B primary colorcomponents illuminating the micromirror element 16 as the light sourcesection 17 is illustrated in FIG. 4(C).

Thus, a light emission period for red light emitted through theactivation of the LED 21 is positioned between light emission periodsfor blue and green light that is produced by blue laser light emitted bythe semiconductor lasers 20A to 20C according to the segmentconfiguration of the color wheel 24. In this case, the period ofinterruption during which red light is emitted is divided such that thefrequency of red light is, for example, six times higher than thefrequency of blue light and the frequency of green light.

When the lighting period for each color is converted into the centralangle of the color wheel 24, the lighting period for red light is20°×6=120°, the lighting period for green light is 40°×3=120°, and thelighting period for blue light is also 40°×3=120°, thus equallytrisecting one frame 360° into 120° each of R, G, B.

The formula below expresses the duty ratio of a period Gr during whichthe micromirror element 16 forms and projects an image with red light byactivating the LED 21 while temporarily stopping oscillation of thesemiconductor lasers 20A to 20C during the period in which the greenphosphor reflective plate 24G of the color wheel 24 is present in theaxes of light from the semiconductor lasers 20A to 20C (i.e., lightsources), as described above.

Gr=r/(r+g+b)

This formula uses a time ratio of r:g:b, at which each of the R, G, andB primary color images is projected relative to one rotation of thecolor wheel through 360°.

By comparison, the formula below expresses the duty ratio of a period Ggduring which the micromirror element 16 forms and projects an image withreflected green light by oscillating the semiconductor lasers 20A to 20Cwhile temporarily stopping the activation of the LED 21 during theperiod in which the green phosphor reflective plate 24G of the colorwheel 24 is present in the axes of light from the semiconductor lasers20A to 20C.

Gg=(g+b)/(r+g+b).

Similarly, the formula below expresses the duty ratio of a period Brduring which the micromirror element 16 forms and projects an image withred light by activation of the LED 21 while temporarily stoppingoscillation of the semiconductor lasers 20A to 20C during the period inwhich the blue phosphor diffusing plate 24B of the color wheel 24 ispresent in the axes of light from the semiconductor lasers 20A to 20C(i.e., light sources).

Br=r/(r+g+b)

By comparison, the formula below expresses the duty ratio of a period Bbduring which the micromirror element 16 forms and projects an image withblue light (i.e., transmission light) by oscillating the semiconductorlasers 20A to 20C while temporarily stopping the activation of the LED21 during the period in which the blue diffusing plate 24B of the colorwheel 24 is present in the axes of light from the semiconductor lasers20A to 20C.

Bb=(g+b)/(r+g+b)

It is known that the LED 21 that produces red light decreases in lightemission efficiency as heat resistance increases with increase intemperature due to continuous activation of the LED 21. However,dividing a light emission period and conducting high-frequency drivemake it possible to avoid decrease in light emission efficiency, thusensuring light emission with stable luminance.

It is also known that the semiconductor lasers 20A to 20C may decreasein light emission efficiency due to a temperature increase resultingfrom continuous oscillation, although the degree of the decrease is notas high as that of the LED 21. Likewise, dividing a light emissionperiod and conducting high-frequency drive make it possible to avoiddecrease in light emission efficiency, thus ensuring light emission withstable luminance.

In synchronization with light emission drive in such a light sourcesection 17, the micromirror element 16 executes a gradation drive foreach primary color image.

As described above, in view of the problem with red phosphor that itemits light by exciting laser light that is low in light emissionluminance compared to that emitted by other color phosphors, the presentembodiment uses the semiconductor lasers 20A to 20C that emit blue lightas a first light source. On the color wheel 24, blue light emitted bythe first light source is converted into blue and green light to be usedas projection light. Red light is emitted by the LED 21, which producesred light as a second light source. Such an optical system configurationallows optical frequency drive that takes into account the lightemission characteristics of each light source, thereby increasing lightemission efficiency and hence stability of the operation. Accordingly,the present embodiment can make color reproducibility compatible withprojected image brightness.

Additionally, in the present embodiment, a color break-up phenomenon,which occurs in a DLP projector, is reliably suppressed by synchronizingthe timing of activation of the LED 21 that produces red light withoutthe color wheel 24, with the timing of switching between the greenphosphor reflective plate 24G and blue diffusing plate 24B of the colorwheel 24. Accordingly, degraded image quality can be avoided.

MODIFIED EXAMPLE

Next, another example of the configuration of the color wheel 24 will bedescribed.

FIG. 5 shows the configuration of a color wheel 24′ different from thecolor wheel 24. As shown in FIG. 5, on the color wheel 24′, a greenphosphor reflective plate 24G with a central angle of 240° and a bluediffusing plate 24B with a central angle of 120° form one ring so thatthe green phosphor reflective plate 24G and the blue diffusing plate 24Bhave a ratio of 2:1.

The wavelength of blue laser light emitted by each of the semiconductorlasers 20A to 20C, the wavelength of green light excited by the greenphosphor reflective plate 24G of the color wheel 24′ illuminated by theblue laser light, and the wavelength of red light produced by the LED 21are the same as those described above.

An operation involving this color wheel 24′ will now be discussed.

In this case, the time ratio at which the R, G, and B primary colorimages composing one frame of a color image to be projected is set to1:2:1. That is, if the time ratio at which each of the R, G, and Bprimary color images is projected is replaced by the central angle ofthe color wheel 24′ relative to one rotation of the color wheel 24′through 360°, 90°:180°:90° is yielded.

The drive timing of a color wheel by a conventional, general drivemethod is shown in FIG. 6(A) for reference. The conventional, generalcolor wheel is driven such that a cycle of R, G, and B segmentscorresponds to one frame.

By comparison, the color wheel 24′ in the present embodiment isconfigured such that the green phosphor reflective plate 24G and theblue diffusing plate 24B bisect the circumference, as shown in FIG. 5,although their proportions are different. Therefore, the projectionlight processing section 31 ensures that one rotation corresponding tothe two segments is synchronized with one frame, as shown in FIG. 6(B).

The projection light processing section 31 trisects the period of thefront ⅔ frame in which the green phosphor reflective plate 24G of thecolor wheel 24′ is present in the optical path of blue laser lightemitted from each of the semiconductor lasers 20A to 20C, and activatesand drives the LED 21 in the first ⅓ of each equal period, therebyproducing red light.

At this time, in synchronization with the activation of the LED 21, thesemiconductor lasers 20A to 20C stop the emission of blue laser light.

Similarly, the projection light processing section 31 trisects theperiod of the last ⅓ frame in which the blue diffusing plate 24B of thecolor wheel 24′ is present in the optical path of blue laser lightemitted from each of the semiconductor lasers 20A to 20C, and activatesand drives the LED 21 in the first ⅓ of each equal period, therebyproducing red light.

At this time, in synchronization with the activation of the LED 21, thesemiconductor lasers 20A to 20C stop the emission of blue laser light.

FIG. 6(D) illustrates the timing of emitting blue laser light from thesemiconductor lasers 20A to 20C, and FIG. 6(E) illustrates the timing ofemitting red light from the LED 21.

Accordingly, the pattern of switching R, G, and B primary colorcomponents illuminating the micromirror element 16 as the light sourcesection 17 is illustrated in FIG. 6(C).

Thus, a light emission period for red light emitted through theactivation of the LED 21 is positioned between light emission periodsfor blue and green light that is produced by blue laser light emitted bythe semiconductor lasers 20A to 20C according to the segmentconfiguration of the color wheel 24. In this case, the period ofinterruption during which red light is emitted is divided such that thefrequency of red light is, for example, six times higher than thefrequency of blue light and the frequency of green light.

When a lighting period for each color is converted into the centralangle of the color wheel 24′, the lighting period for red light is20°×3+10×3=90°, the lighting period for green light is 60°×3=180°, andthe lighting period for blue light is 30°×3=90°, thus, dividing oneframe 360° into R, G, B at a ratio of 1:2:1.

In synchronization with light emission drive for such a light sourcesection 17, the micromirror element 16 executes gradation drive for eachprimary color image.

In the modified example described above, since the ratio of the periodfor the green phosphor reflective plate 24G of the color wheel 24′ andthe ratio of the period for the blue diffusing plate 24B are differentfrom each other, the light emission period for the LED 21 is positionedbetween the period for the green phosphor reflective plate 24G and theperiod for the blue diffusing plate 24B in the same ratio but atdifferent times. Accordingly, the time ratio among the R, G, and B ofone frame can be suitably maintained.

In the foregoing embodiment, a description has been given using anexample where, while the semiconductor lasers 20A to 20C emit blue laserlight, thereby causing the color wheel 24 (24′) to produce blue lightand green light, the LED 21 produces red light. However, the presentinvention is not limited to this but can equally be applied to aprojection apparatus that uses a light source section or the like, whichis designed such that if the primary colors produced by a single lightsource are unequal in luminance, another light source compensates forthe unequal luminance.

The description given above is an example where the present invention isapplied to a DLP (registered trademark) data projector apparatus.However, the present invention can equally be applied to, for instance,a liquid crystal projector that forms an optical image by using atransmission-type monochrome liquid crystal panel.

For example, even when some of the constituent elements of theconfigurations of the embodiments described above are omitted, thismodified configuration is included in the present invention as long asthe same effect can be obtained.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

What is claimed is:
 1. A light source device comprising: a first lightsource configured to emit light within a first wavelength band; a secondlight source configured to emit light within a second wavelength band;and a light source control section configured to control drive timing ofthe first light source with a first drive pattern, and to control drivetiming of the second light source with a second drive pattern which isan inverted pattern of the first drive pattern of the first lightsource, such that a light emission period for light-source light usinglight emitted by the second light source is positioned between lightemission periods for the light-source light emitted by the first lightsource, and such that a frequency of the light-source light using lightemitted by the second light source is higher than a frequency of lightemitted by the first light source.
 2. The light source device accordingto claim 1, wherein the light source control section intermittentlydrives the first light source at predetermined time intervals, andintermittently drives the second light source such that the second lightsource is activated during intermittent periods of the first lightsource.
 3. The light source device according to claim 1, wherein thelight source control section controls the drive timing for each of thefirst light source and the second light source such that the lightemission period for the light-source light using light emitted by thesecond light source is positioned between the light emission periods forthe light-source light emitted by the first light source, and such thatthe frequency of the light-source light using light emitted by thesecond light source is synchronized with the frequency of light emittedby the first light source and the frequency of the light-source lightusing light emitted by the second light source is a plurality of timeshigher than the frequency of light emitted by the first light source. 4.The light source device according to claim 1, further comprising a thirdlight source configured to emit light within a third wavelength band;wherein the light source control section is configured to control drivetiming of the second light source with the second drive pattern, and tocontrol drive timing of the third light source with a third drivepattern which is an inverted pattern of the second drive pattern of thesecond light source, such that a light emission period for light-sourcelight using light emitted by the second light source is positionedbetween light emission periods for the light-source light emitted by thethird light source, and such that a frequency of the light-source lightusing light emitted by the second light source is higher than afrequency of light emitted by the third light source.
 5. The lightsource device according to claim 4, wherein the third light sourcecomprises a light-source light production section configured to producelight-source light within the third wavelength band by using lightemitted by the first light source.
 6. A projection apparatus comprising:a first light source configured to emit light within a first wavelengthband; a second light source configured to emit light within a secondwavelength band; a light source control section configured to controldrive timing of the first light source, and to control drive timing ofthe second light source; an input section configured to input an imagesignal; and a projection section configured to use light-source lightemitted based on the control of the light source control section and toform and project a color optical image corresponding to the image signalinput through the input section; wherein the light source controlsection is configured to control drive timing of the first light sourcewith a first drive pattern, and to control drive timing of the secondlight source with a second drive pattern which is an inverted pattern ofthe first drive pattern of the first light source, such that a lightemission period for light-source light using light emitted by the secondlight source is positioned between light emission periods for thelight-source light emitted by the first light source, and such that afrequency of the light-source light using light emitted by the secondlight source is higher than a frequency of light emitted by the firstlight source.
 7. The projection apparatus according to claim 6, whereinthe light source control section intermittently drives the first lightsource at predetermined time intervals, and intermittently drives thesecond light source such that the second light source is activatedduring intermittent periods of the first light source.
 8. The projectionapparatus according to claim 6, wherein the light source control sectioncontrols the drive timing for each of the first light source and thesecond light source such that the light emission period for thelight-source light using light emitted by the second light source ispositioned between the light emission periods for the light-source lightemitted by the first light source, and such that the frequency of thelight-source light using light emitted by the second light source issynchronized with the frequency of light emitted by the first lightsource and the frequency of the light-source light using light emittedby the second light source is a plurality of times higher than thefrequency of light emitted by the first light source.
 9. The projectionapparatus according to claim 6, further comprising a third light sourceconfigured to emit light within a third wavelength band; wherein thelight source control section is configured to control drive timing ofthe second light source with the second drive pattern, and to controldrive timing of the third light source with a third drive pattern whichis an inverted pattern of the second drive pattern of the second lightsource, such that a light emission period for light-source light usinglight emitted by the second light source is positioned between lightemission periods for the light-source light emitted by the third lightsource, and such that a frequency of the light-source light using lightemitted by the second light source is higher than a frequency of lightemitted by the third light source.
 10. The projection apparatusaccording to claim 9, wherein the third light source comprises alight-source light production section configured to produce light-sourcelight within the third wavelength band by using light emitted by thefirst light source.
 11. A projection method for a projection apparatusincluding a first light source configured to emit light within a firstwavelength band, a second light source configured to emit light within asecond wavelength band, a light source control section configured tocontrol drive timing of each of the first light source and the secondlight source, an input section configured to input an image signal, anda projection section configured to use the light-source light emittedbased on the control of the light source control section and form andproject a color optical image corresponding to the image signal inputthrough the input section, the method comprising: controlling drivetiming of the first light source with a first drive pattern andcontrolling drive timing of the second light source with a second drivepattern which is an inverted pattern of the first drive pattern of thefirst light source, such that a light emission period for light-sourcelight using light emitted by the second light source is positionedbetween light emission periods for the light-source light emitted by thefirst light source, and such that a frequency of the light-source lightusing light emitted by the second light source is higher than afrequency of light emitted by the first light source.